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wag Arrow/575' United States Patent C) 3,172,598 METHOD OF CONTROLLINGWORK MOVEMENT Gordon B. Carson and Walter L. Starkey, Columbus,

Ohio, assignors to The Shelby Shoe Company, Portsmouth, Ohio, acorporation of Ohio Original application Mar. 7, 1957, Ser. No. 644,566,now Patent No. 3,083,580, dated Apr. 2, 1963. Divided and thisapplication Aug. 28, 1962, Ser. No. 221,400 6 Claims. (Cl. 2343) Thisinvention relates to a novel method by means of which a punched tape orother record is produced from a pattern; and is used to control a drivefor elfecting relative movement between a work carrying platen and atool, so that the tool engages the work at predetermined intervals alongthe pattern. The present application is a divisional application of ourUnited States patent application Serial No. 644,566, filed March 7,1957, now United States Patent No. 3,083,580.

The present invention is of particular utility when used for guidingmovements of work in stitching machines, spot welding devices, heat andpressure machines for joining plastic materials, stapling machines, andthe like. In these and other types of cyclically operable tools, it isfrequently desirable not only to control the contour along which work ismoved relative the tool, but also the amount the work is advancedbetween each successive actuation of the tool. In general, such devicesare to be contrasted with various metal working machines such as,contour burning machines, and the like in which the only problem is tocontrol the contour along which the work is moved relative to the tool,the rate of work advancemerit not being of critical importance.

In order to provide a fuller understanding of the present invention, itwill be discussed in detail with reference to a stitching machine of thetype used to fasten multi-thicknesses of material together, or to stitcha decorative pattern on a single thickness of material. It is to beunderstood that many of the problems inherent in the operation of such adevice are also present in other types of equipment; and that some orall of the advantages provided by the present invention make itextremely useful for embodiment in other devices.

Stitching machines are used in large numbers in many industries, such asthe shoe industry. At the present time, it is conventional in suchcommercial stitching operations to rely upon skilled operators whomanually guide the articles to be stitched beneath the sewing machinehead. Two problems result from this type of operation. In the firstplace, hand stitching, especially of complex decorative patterns of thetype frequently used in womens shoes, introduces an excessively highlabor cost. Furthermore, even skilled operators do not accuratelyreproduce the desired pattern with a uniform stitch length, so that theappearance of the finished article is not as attractive as the originaldesign.

It is the principal object of the present invention to provide a methodfor automatically guiding work relative to a tool, such as a stitchingmachine head so that the original pattern is accurately reproduced and auniform stitch spacing is obtained. In accordance with the presentmethod, a record, such as a punched or magnetic tape is prepared fromthe original stitching pattern. This tape is then employed to controlone or more automatic stitching machines so that the worktable, orplaten, is automatically moved in accordance with the information storedon the tape to reproduce accurately the original pattern. Moreover, asexplained below, in accordance with the present method the platen isshifted a substantially equal distance along the pattern between eachsuccessive needle penetration, so that not only does the 3,172,598Patented Mar. 9, 1965 stitching follow the desired pattern, but thestitches are of substantially the same length, thereby greatly enhancingthe attractiveness of the stitched article.

One form of apparatus which can be operated in accordance with thepresent method is a stitching machine including a stationary headsupporting a conventional reciprocating needle. A worktable is mountedfor universal movement beneath the needle. Two component drivemechanisms are provided, each drive being effective to control movementof the worktable along one of two perpendicular axes. By combiningmovements along the two axes, the worktable can be shifted in anydesired direction to bring any point on the table into registry with theneedle. Movement along each axis is eliected in multiples of a smallunit increment such as, for example, .005. Since the two correspondingaxes of movement are at right angles to one another, the net or theresultant, movement of the worktable is the vector sum of the twocomponent movements and its length is equal to the hypotenuse of theright triangle formed by the two component movements.

It is the concept of the present invention to shift the worktable alongthe pattern in a succession of movements; each movement taking placewhile the needle is out of engagement with the work and beingconstituted by component movements along each of the axes. Each set ofcomponent movements has substantially the same vector sum or hypotenuselength. For example, if the desired stitch length (or hypotenuse length)is equal to 13 increments of movement, the platen is always shifted bymeans of one of the following pairs of component movements; it beingunderstood that the increments of movement can take place along eitheraxis; 0 and 13, l and 13, 2 and 13, 3 and 12, 4 and 12, 5 and 12, 6 and11, 7 and 11, 8 and 10, or 9 and 9. The variation in stitch length dueto the small differences in hypotenuse length resulting from thesecombinations is imperceptible. However, if for some particularapplication, still greater accuracy is desired, it can readily beobtained by increasing the number of increments of hypotenuse length andmaking each individual increment smaller.

One preferred form of apparatus for practicing the present method ofproducing a record to control platen movement includes a curve followerwhich is adapted to trace a stitching pattern plotted to scale andoriented relative to two perpendicular axes corresponding to the axes ofworktable movement. Starting from a predetermined point on the pattern,the tracing head moves along the pattern and actuates two coordinatesignal generators which produce an electrical signal for each incrementof movement along the axes. These signals are applied to binary counterswhich count and store the number of signals. As explained below, each ofthe signal generators is effective to indicate the direction along theaxis in which the follower moves between signal pulses. The outputsignals from the binary counters are employed to condition tape punchesfor actuation. Additional signals from the binary adders are alsoapplied to a stitch spacing control circuit which is effective to causeactuation of the conditioned punches to form one set of instructions onthe tape Whenever the two component movements correspond to one of theselected pairs, such as one of those listed above. As soon as theinstructions are punched in the tape, the binary counters areautomatically reset to 0 to prepare them for further counting as thetracing head moves over the pattern.

When the tape or other record has been prepared indicating each of thesuccessive movements required to completely traverse the pattern, thetape is inserted in a suitable reader adapted to produce electricalsignals corresponding to the binary coded information stored in thetape. These electrical signals are decoded either electrically ormechanically and are used to actuate solenoids which control gears inthe component drive units. These gears have different pitches so thatdepending upon which gear is engaged, the platen is driven from to themaximum number of increments desired (13 in the embodiment discussedabove).

These and other objects and advantages of the present invention will bemore readily apparent from a consideration of the following detaileddescription of the drawings illustrating a preferred embodiment of theinvention.

In the drawings:

FIGURE 1 is a schematic block diagram of the mechanism and circuits forpunching a control tape;

FIGURE 2 is a schematic block diagram of the mecha nism and circuits fortransforming the information stored on a punched tape to movements of aWorktable;

FIGURE 3 is a top plan view of one suitable form of pattern tracingapparatus;

FIGURE 4 is an enlarged top view, partially broken away of the tracinghead shown in FIGURE 3;

FIGURE 5 is a cross-sectional view of the tracing head taken along line55 of FIGURE 4;

FIGURE 6 is a semi-diagrammatic view partially in section of onesuitable form of coordinate signal generat ing unit;

FIGURE 7 is a side view showing the perforated disc of a coordinatesignal generating unit;

FIGURE 8 is a greatly enlarged segment of a pattern illustrating the wayin which the pattern is broken up into increments of componentmovements;

FIGURE 9 is a schematic circuit diagram of the tape punching controlcircuit;

FIGURE 10 is an enlarged view of two segments of tape punched incorrespondence with the movements re quired to reproduce the pattern ofFIGURE 8;

FIGURE 11 is a schematic circuit diagram of a stitch spacing controlcircuit, including X and Y component coding circuits;

FIGURE 12 is a schematic circuit diagram similar to FIGURE 11 showingthe manner in which the stitch spacing control circuit is adjusted tovary the stitch spacing;

FIGURES 13 and 14 are schematic circuit diagrams of a prefrred form ofbinary adder and subtractor;

FIGURE 15 is a schematic circuit diagram of the tape reader, decodingcircuit, and the solenoid energiz ing circuit of the platen drivingmechanism;

FIGURE 16 is a chart illustrating the sequence of operation of astitching machine, tape reading device and driving solenoids;

FIGURE 17 is a top view partially broken away of a component drive unitfor a work holding platen;

FIGURE 18 is a cross-sectional view taken along line 1318 of FIGURE 17;

FIGURE 19 is a cross-sectional view taken along line 19-19 of FIGURE 17;

FIGURE 20 is a cross-sectional view taken along line 20-20 of FIGURE 17;

FIGURE 21 is a top plan view of a stitching machine worktable andworktable driving mechanism;

FIGURE 22 is a top plan view of a mechanical decoder and gear unit, aportion of the cover being broken away to show details of construction;

FIGURE 23 is a cross-sectional view taken along line 2323 of FIGURE 22;and

FIGURE 24 is a cross-sectional view taken along line 24-24 of FIGURE 23.

GENERAL DISCRIPTION One preferred machine adapted to be operated inaccordance with the present method, as shown in the drawings anddescribed in detail below, is an automatic stitching machine in whichmaterial is moved past a rcciprocating needle in such a manner thatirrespective of the contour being stitched, the stitches will besubstantially uniformly spaced. From the foregoing discussion of thegeneral principles of the invention and the following detaileddescription of this particular embodiment; those skilled in the art willreadily comprehend the various modifications to which the invention issusceptble. For example, the control circuits and platen shiftingmechanism described herein can readily be employed to shift workrelative to any type of tool in which it is desirable to control therate of work movement past the tool as well as the path along which thework is advanced. One such device is a seam Welder; another is a heatsealing device for joining plastic material. An additional applicationof the circuits and mechanism of the present invention is to machines inwhich it is desirable to present a work piece to a tool so that aplurality of operations are performed at equispaced points along apredetermined pattern. For example, in spot welding it is frequentlydesirable to present work to welding electrodes so that equispaced weldsare made along a particular pattern.

In general, an automatic stitching machine comprises a follower fortracking along a pattern and means for producing a record of thefollower movements. This rec- 0rd is subsequently utilized to controlapparatus for shifting a Work holding platen beneath a reciprocatingneedle; the record being effective to cause the platen to reproduce themovements originally made by the follower in tracing the pattern.

FIGURE 1 discloses the general circuit arrangement for producing arecord on an intelligence medium which can later be used to controlmovements of a Worktable so that a workpiece will be moved beneath thetool in accordance with the desired pattern. As shown in FIG URE 1, afollower 10 is moved along the pattern 11 to be reproduced. The followeris mounted for universal movement along the plane of the pattern 11 andis connected by suitable linkages to two coordinate signal generators 12and 13. Each coordinate signal generator is responsive to the componentmovements of the follower along one of two axes angulated with respectto one another. These axes are preferably disposed at right angles toone another, although a workable device could be constructed using twocoordinate axes disposed at some other angle.

In the embodiment shown, follower movements and subsequent correspondingmovements of a work holding platen, are accomplished by combinedmovements along a first axis (horizontal in the drawing) referred to asan X axis and a second axis (vertical in the drawings)- referred to as aY axis. Movements of the follower along each axis are divided intoincrements of a predetermined length; for example, .005 inch. Two signalgenerators are connected to the follower. Each signal generator iseifective to generate a pulse for each increment of travel of thefollower along the axis with which the signal generator is associated.Each coordinate signal generator is also effective, as explained ingreater detail below, to indicate by the sequence in which pulses areproduced the direction along the axis in which the follower is beingshifted.

The output from each signal generator is applied to a binary counter. Asexplained in greater detail below, a binary counter is effective tocount and store the number of pulses generated by each coordinate signalgenerator. A signal corresponding to this number is produced by thebinary counter and is applied to a record forming device, in thisembodiment, a tape perforator.

In the perforator this signal is effective to condition a,

plurality of punches for actuation so that a tape will be: punched inconformity with the number of pulses re ceived by the counters. I

The output of each of the counters is also applied toa stitch spacingcontrol circuit, which functions to control the length of pattern alongwhich the work is advanced between successive needle penetrations. Thatis, be

1. A METHOD OF MAKING PERFORATED TAPES FOR SHIFTING WORKING RELATIVE TOA STITCHING MACHINE SO THAT THE WORK IS STITCHED ALONG A PREDETERMINEDPATTERN WITH SUBSTANTIALLY UNIFORM STITCH SPACING, SAID METHODCOMPRISING THE STEPS OF PLOTTING THE PATTERN TO BE STITCHED TO SCALERELATIVE TO TWO PERPENDICULAR AXES, COUNTING THE NUMBER OF COMPONENTINCREMENTS ALONG EACH OF SAID AXES AS THE PATTERN IS TRAVEERSED ANDPEERFORATING THE TAPES TO INDICATE THE NUMBER OF INCREMENTS OF MOVEMENTALONG EACH OF SAID AXES WHENEVER THE HYPOTENUSE LENGTH OF SAIDINCREMENTS EQUALS THE PREDETERMINED STITCH LENGTH.